This might once have been the kind of game that the brittle Manchester United teams of the post-Alex Ferguson era would have failed to win, and Jose Mourinho is entitled to bring up that point first before anyone taps him on the shoulder and asks why it was so low on style.

This might once have been the kind of game that the brittle Manchester United teams of the post-Alex Ferguson era would have failed to win, and Jose Mourinho is entitled to bring up that point first before anyone taps him on the shoulder and asks why it was so low on style.

This was United's third straight Champions League victory in their return to the competition, and they now look certain to qualify for the knockout round after Christmas, although after that goalless draw at Anfield this was little better for the pure entertainment.

The winner was an own goal from the 18-year-old goalkeeper Mile Svilar who caught a Marcus Rashford free-kick in the second half and stumbled backwards over his own goal-line.

It was a strange way to decide a European tie, against a Benfica team who were for the most part dreadful and had the veteran defender Luisao sent off in time added on at the end for a second yellow card.

There may well have been goals elsewhere in the Champions League on this night but Mourinho seemed to know exactly what was required to beat the club whom he first managed, and his current United side delivered that performance.

They were led by Nemanja Matic, who has been crucial in midfield for Mourinho in recent weeks. As at Anfield, they were required to hold the line late in the game as Benfica came in search of the equaliser. The reality was that United on a good day at home would have been capable of sweeping this level of opposition aside.

There was precious little enthusiasm among the fans of Benfica for this meeting of old European names, and it was quite a shock to see the Stadium of Light around half-full and a mood of indifference spread to the pitch too.

Mourinho had made four changes from the side that had ground out a draw at Anfield on Saturday and while this one showed a fraction more imagination, there was not much in it judging by a first half in which there was scarcely a chance.

Romelu Lukaku crashed a header against the bar but was judged to have fouled Benfica's teenage goalkeeper Svilar in the process.

The Portuguese champions are currently third in the Primeira Liga but it is their form in the Champions League group stages before this game that might have accounted for the modest crowd.

They had already lost 2-1 to CSKA Moscow at home before they were thrashed 5-0 by Basel in Switzerland in the previous round of games and it was hard to spot the man who might win them the game in the first half.

Despite that, United were ponderous in their build-up and, Rashford aside, were a team notable for their lack of pace.

The inclusion of Juan Mata and Henrikh Mkhitaryan did not seem to help Mourinho's team retain the ball and United did not work young Svilar before the break, as one might have expected an experienced team facing a rookie in goal to do.

The goal came when Svilar had already made the sort of small errors that suggested he was not coping with the demands of the game.

He had been forced to punch a ball over the bar because his positioning was wrong and he had lost the flight and then, with 20 minutes of the second half played came the goal.

Perhaps Rashford had noticed the jitters of his fellow teenager before he took a free-kick from the left channel that had Svilar backtracking towards goal.

The teenager must have been unaware of his position because even punching or slapping the ball out would have been preferable to hanging on to it, which the Belgian did and consequently carried it back over the line and into the goal.

It was made all the more unfortunate that when Svilar did finally take it back across the line, he was still holding the ball out as far as he could away from him, but to no avail. The German referee Felix Zwayer checked his goal-decision system although it was not hard to see that the ball had crossed.

There was embarrassment and despair on the face of the young goalkeeper and one can only hope that the talent which has taken him this far, through the ranks of Belgium's junior international teams, will sustain him in the future.